Compositions and processes for photolithography

ABSTRACT

Topcoat layer compositions are provided that are applied above a photoresist composition. The compositions find particular applicability to immersion lithography processing.

This application claims the benefit under 35 U.S.C. §119(e) of U.S.Provisional Application No. 61/204,030, filed Dec. 31, 2008, the entirecontents of which are herein incorporated by reference.

This invention relates to topcoat layer compositions that may be appliedabove a photoresist composition in photolithography processing, such asimmersion lithography processing. The invention finds particularapplicability as a topcoat layer in an immersion lithography process forthe formation of semiconductor devices.

Photoresists are photosensitive films used for transfer of an image to asubstrate. A coating layer of a photoresist is formed on a substrate andthe photoresist layer is then exposed through a photomask to a source ofactivating radiation. The photomask has areas that are opaque to theactivating radiation and other areas that are transparent to theactivating radiation. Exposure to activating radiation provides aphotoinduced chemical transformation of the photoresist coating tothereby transfer the pattern of the photomask to the photoresist coatedsubstrate. Following exposure, the photoresist is developed by contactwith a developer solution to provide a relief image that permitsselective processing of the substrate.

One approach to achieving nanometer (nm)-scale feature sizes insemiconductor devices is to use shorter wavelengths of light. However,the difficulty in finding materials that are transparent below 193 nmhas led to the immersion lithography process to increase the numericalaperture of the lens by use of a liquid to focus more light into thefilm. Immersion lithography employs a relatively high refractive indexfluid between the last surface of an imaging device (e.g., KrF or ArFlight source) and the first surface on the substrate, for example, asemiconductor wafer. When using water (refractive index of 1.44 at awavelength of 193 nm) as the immersion fluid, a line width at 193 nm of35 nm is possible.

In immersion lithography, direct contact between the immersion fluid andphotoresist layer can result in leaching of components of thephotoresist into the immersion fluid. This leaching can causecontamination of the optical lens and bring about a change in theeffective refractive index and transmission properties of the immersionfluid. In an effort to ameliorate this problem, use of a topcoat layerover the photoresist layer as a barrier between the immersion fluid andunderlying photoresist layer has been proposed. The use of topcoatlayers in immersion lithography, however, presents various challenges.Topcoat layers can affect, for example, the process window, criticaldimension (CD) variation and resist profile depending on characteristicssuch as topcoat refractive index, thickness, acidity, chemicalinteraction with the resist and soaking time. In addition, use of atopcoat layer can negatively impact device yield due, for example, tomicro-bridging defects which prevent proper resist pattern formation.

To improve performance of topcoat materials, the use of self-segregatingtopcoat compositions to form a graded topcoat layer has been proposed,for example, in Self-segregating Materials for Immersion Lithography,Daniel P. Sanders et al, Advances in Resist Materials and ProcessingTechnology XXV, Proceedings of the SPIE, Vol. 6923, pp.692309-1-692309-12 (2008). A graded topcoat would theoretically allowfor a tailored material having desired properties at both the immersionfluid and photoresist interfaces, for example, a high water recedingangle at the immersion fluid interface and good developer solubility atthe photoresist interface.

There is a continuing need in the art for improved self-segregatingtopcoat compositions for use in immersion lithography, and for theirmethods of use.

Provided are new topcoat compositions and processes for immersionphotolithography. Also provided are new compositions that can be used asan overcoat layer above a photoresist layer for use in non-immersionimaging processes.

In accordance with a first aspect of the invention, provided arecompositions suitable for use in forming a topcoat layer over a layer ofphotoresist. The composition includes a first resin, a second resin anda third resin which are different from each other. The first resincomprises one or more fluorinated groups and is present in thecomposition in a larger proportion by weight than the second and thirdresins individually. The second resin has a lower surface energy than asurface energy of the first resin and the third resin. The third resincomprises one or more strong acid groups.

In a further aspect of the invention, the first resin further comprisesa sulfonamide. In a further aspect, the second resin comprises one ormore photoacid-labile groups. In a further aspect, the one or morestrong acid groups of the third resin comprise a sulfonic acid group. Ina further aspect, the composition further comprises a solvent systemcomprising a mixture of: an alcohol; an alkyl ether and/or an alkane;and a dialkyl glycol mono-alkyl ether.

In accordance with a further aspect of the invention, provided arecoated substrates. The coated substrates include: a photoresist layer ona substrate; and a topcoat layer on the photoresist layer. The topcoatlayer comprises: a first resin, a second resin and a third resin whichare different from each other. The first resin comprises one or morefluorinated groups and is present in the composition in a largerproportion by weight than the second and third resins individually. Thesecond resin has a lower surface energy than a surface energy of thefirst resin and the third resin. The third resin comprises one or morestrong acid groups. In accordance with a further aspect, the topcoatlayer is a graded layer.

In accordance with a further aspect of the invention, methods ofprocessing a photoresist composition are provided. The methods include:(a) applying a photoresist composition over a substrate to form aphotoresist layer; (b) applying over the photoresist layer a topcoatcomposition as described above with respect to the first aspect; and (c)exposing the photoresist layer to actinic radiation. In accordance witha further aspect of the method, the exposure can be an immersionexposure and the substrate can be a semiconductor wafer.

In certain aspects, topcoat layer compositions of the invention that areapplied above a photoresist composition layer are self-segregating andform a graded topcoat layer, which can help at least to inhibit, andpreferably to minimize or prevent, migration of components of thephotoresist layer into an immersion fluid employed in an immersionlithography process. In addition, the water dynamic contact anglecharacteristics at the immersion fluid interface, such as the waterreceding angle, can be improved. Still further, the topcoat layercompositions provide topcoat layers having excellent developersolubility for both exposed and unexposed regions of the layer, forexample, in an aqueous base developer.

As used herein, the term “immersion fluid” means a fluid (e.g., water)interposed between a lens of an exposure tool and a photoresist coatedsubstrate to conduct immersion lithography.

Also as used herein, a topcoat layer will be considered as inhibitingthe migration of photoresist material into an immersion fluid if adecreased amount of acid or organic material is detected in theimmersion fluid upon use of the topcoat composition relative to the samephotoresist system that is processed in the same manner, but in theabsence of the topcoat composition layer. Detection of photoresistmaterial in the immersion fluid can be conducted through massspectroscopy analysis of the immersion fluid before exposure to thephotoresist (with and without the overcoated topcoat composition layer)and then after lithographic processing of the photoresist layer (withand without the overcoated topcoat composition layer) with exposurethrough the immersion fluid. Preferably, the topcoat compositionprovides at least a 10 percent reduction in photoresist material (e.g.,acid or organics as detected by mass spectroscopy) residing in theimmersion fluid relative to the same photoresist that does not employany topcoat layer (i.e., the immersion fluid directly contacts thephotoresist layer), more preferably the topcoat composition provides atleast a 20, 50, or 100 percent reduction in photoresist materialresiding in the immersion fluid relative to the same photoresist thatdoes not employ a topcoat layer.

In certain aspects, one or more resins of the topcoat composition willhave two distinct repeat units (copolymers), three distinct repeat units(terpolymers), four distinct repeat units (tetra-polymers), fivedistinct repeat units (pentapolymers), or even higher order polymers.

Typical resins of the topcoat compositions of the invention may containa variety of repeat units, including repeat units including, forexample, one or more: hydrophobic groups; weak acid groups; strong acidgroups; branched optionally substituted alkyl or cycloalkyl groups;fluoroalkyl groups; or polar groups, such as ester, ether, carboxy, orsulfonyl groups.

In certain aspects, one or more resins of the coating composition willcomprise one or more groups that are reactive during lithographicprocessing, for example, one or more photoacid labile groups that canundergo cleavage reactions in the presence of acid and heat, such asacid-labile ester groups (e.g., t-butyl ester groups such as provided bypolymerization of t-butyl acrylate or t-butylmethacrylate,adamantylacrylate) and/or acetal groups such as provided bypolymerization of a vinyl ether compound.

The topcoat compositions of the invention may comprise a variety ofmaterials, and typical resins of the compositions are higher molecularweight materials such as materials having a molecular weight in excessof about 3000, 4000 or 4500 daltons. One or more resins of thecompositions can have a molecular weight in excess of 6000, 7000, 8000or 9000 daltons.

The topcoat compositions of the invention may comprise one or moreoptional components in addition to the resin components, for example:one or more acid generator compounds such as one or more thermal acidgenerator (TAG) compounds and/or one or more photoacid generator (PAG)compounds; and one or more surfactant compounds.

It has been found that topcoat compositions of the invention can exhibitfavorable static and dynamic water contact angles as evaluated in animmersion lithography process. See Burnett et al., J. Vac. Sci. Techn.B, 23(6), pages 2721-2727 (November/December 2005) for a discussion ofsuch water contact angles.

Typical imaging wavelengths of lithographic systems of the inventioninclude sub-300 nm wavelengths such as 248 nm, and sub-200 nmwavelengths such as 193 nm. Particularly preferred photoresists for usein systems of the invention may contain a photoactive component (e.g.,one or more photoacid generator compounds) and one or more resins thatare chosen from among:

1) a phenolic resin that contains acid-labile groups that can provide achemically amplified positive resist particularly suitable for imagingat 248 nm. Particularly preferred resins of this class include: i)polymers that contain polymerized units of a vinyl phenol and an alkylacrylate, where the polymerized alkyl acrylate units can undergo adeblocking reaction in the presence of photoacid. Exemplary alkylacrylates that can undergo a photoacid-induced deblocking reactioninclude t-butyl acrylate, t-butyl methacrylate, methyladamantylacrylate, methyl adamantyl methacrylate, and other non-cyclic alkyl andalicyclic acrylates that can undergo a photoacid-induced reaction, suchas polymers described in U.S. Pat. Nos. 6,042,997 and 5,492,793; ii)polymers that contain polymerized units of a vinyl phenol, an optionallysubstituted vinyl phenyl (e.g. styrene) that does not contain a hydroxyor carboxy ring substituent, and an alkyl acrylate such as thosedeblocking groups described with polymers i) above, such as polymersdescribed in U.S. Pat. No. 6,042,997; and iii) polymers that containrepeat units that comprise an acetal or ketal moiety that will reactwith photoacid, and optionally aromatic repeat units such as phenyl orphenolic groups; such polymers have been described in U.S. Pat. Nos.5,929,176 and 6,090,526, as well as blends of i) and/or ii) and/or iii);

2) a resin that is substantially or completely free of phenyl or otheraromatic groups that can provide a chemically amplified positive resistparticularly suitable for imaging at sub-200 nm wavelengths such as 193nm. Particularly preferred resins of this class include: i) polymersthat contain polymerized units of a non-aromatic cyclic olefin(endocyclic double bond) such as an optionally substituted norbornene,such as polymers described in U.S. Pat. Nos. 5,843,624, and 6,048,664;ii) polymers that contain alkyl acrylate units such as t-butyl acrylate,t-butyl methacrylate, methyladamantyl acrylate, methyl adamantylmethacrylate, and other non-cyclic alkyl and alicyclic acrylates; suchpolymers have been described in U.S. Pat. No. 6,057,083; EuropeanPublished Applications EP01008913A1 and EP00930542A1; and U.S. Pat. No.6,136,501, and iii) polymers that contain polymerized anhydride units,particularly polymerized maleic anhydride and/or itaconic anhydrideunits, such as disclosed in European Published Application EP01008913A1and U.S. Pat. No. 6,048,662, as well as blends of i) and/or ii) and/oriii);

3) a resin that contains repeat units that contain a hetero atom,particularly oxygen and/or sulfur (but other than an anhydride, i.e.,the unit does not contain a keto ring atom), and preferable aresubstantially or completely free of any aromatic units. Preferably, theheteroalicyclic unit is fused to the resin backbone, and furtherpreferred is where the resin comprises a fused carbon alicyclic unitsuch as provided by polymerization of a norbornene group and/or ananhydride unit such as provided by polymerization of a maleic anhydrideor itaconic anhydride. Such resins are disclosed in InternationalApplication Pub. No. WO 01/86353 A1 and U.S. Pat. No. 6,306,554.

4) a resin that contains fluorine substitution (fluoropolymer), forexample, as may be provided by polymerization of tetrafluoroethylene, afluorinated aromatic group such as fluoro-styrene compound, compoundsthat comprise a hexafluoroalcohol moiety, and the like. Examples of suchresins are disclosed, for example, in International Application Pub. No.WO2000017712.

In immersion lithography methods of the invention, an immersion fluidhaving a refractive index of between about 1 and about 2 is suitablymaintained between an exposure tool and the topcoat composition duringthe exposing. A variety of photoresists may be employed in these methodsof the invention, for example, chemically-amplified positive-actingphotoresists and negative-acting photoresists.

In some aspects of these methods of the invention the photoresistcomposition will not be not thermally treated prior to applying theovercoated topcoat composition. Also, in some aspects of these methodsof the invention, the substrate with the applied photoresist compositionand topcoat composition is thermally treated prior to exposing to removesolvent from both the applied photoresist composition and the appliedtopcoat composition.

Methods and systems of the invention can be used with a variety ofimaging wavelengths, for example, radiation having a wavelength of lessthan 300 nm such as 248 nm or less than 200 such as 193 nm.

Topcoat Compositions

The topcoat compositions of the invention include three or moredifferent resins. Resins useful in the invention may be homopolymers,but more typically include a plurality of distinct repeat units, withtwo or three distinct units, i.e., copolymers or terpolymers, beingtypical.

A variety of resins may be employed in the topcoat compositions of theinvention, including resins comprising polymerized acrylate groups,polyesters, and other repeat units and/or polymer backbone structuressuch as provided by, for example, poly(alkylene oxide),poly(meth)acrylic acid, poly (meth)acrylamides, polymerized aromatic(meth)acrylates, and polymerized vinyl aromatic monomers. Typically, theresins each include at least two differing repeat units, morepreferably, at least two of the first, second and third resins includeat least three differing repeat units. The different resins suitably maybe present in varying relative amounts.

The resins of the topcoat compositions of the invention may contain avariety of repeat units, including repeat units including, for example,one or more: hydrophobic groups; weak acid groups; strong acid groups;branched optionally substituted alkyl or cycloalkyl groups; fluoroalkylgroups; or polar groups, such as ester, ether, carboxy, or sulfonylgroups. The presence of particular functional groups on the repeat unitsof the resins will depend, for example, on the intended functionality ofthe resin.

In certain preferred aspects, one or more resins of the coatingcomposition will comprise one or more groups that are reactive duringlithographic processing, for example, one or more photoacid-acid labilegroups that can undergo cleavage reactions in the presence of acid andheat, such as acid-labile ester groups (e.g., t-butyl ester groups suchas provided by polymerization of t-butyl acrylate ort-butylmethacrylate, adamantylacrylate) and/or acetal groups such asprovided by polymerization of a vinyl ether compound. The presence ofsuch groups can render the associated resin(s) more soluble in adeveloper solution, thereby aiding in developability and removal of thetopcoat layer during a development process.

The resins of the topcoat compositions typically have relatively highmolecular weights, for example, in excess of about 3000, 4000 or 4500,daltons. One or more resins of the compositions can have a molecularweight in excess of 6000, 7000, 8000 or 9000 daltons.

The resin systems of the inventive topcoat compositions include three ormore distinct resins. The resins can advantageously be selected totailor characteristics of the topcoat layer, with each generally servinga particular purpose or function. Such functions include, for example,one or more of photoresist profile adjusting, topcoat surface adjusting,reducing defects and reducing interfacial mixing between the topcoat andphotoresist layers. Preferable resin systems of the invention include amatrix resin, generally the resin present in the composition in thelargest proportion on an individual basis and typically forming a majorportion of the topcoat film, and two or more additive resins. At leastone additive resin is present for surface adjusting purposes, forexample, for improving immersion fluid contact angle characteristics. Asecond additive resin is present for tuning of the resist featureprofile and control of resist top loss.

Exemplary such resins useful in the invention will now be described. Thematrix resin may include, for example, one or more repeating units, withtwo repeating units being typical. The matrix resin should provide asufficiently high developer dissolution rate for reducing overalldefectivity due, for example, to micro-bridging. The matrix resin mayinclude, for example, a sulfonamide-containing monomer for enhancing thepolymer developer dissolution rate. A typical developer dissolution ratefor the matrix polymer is greater than 500 nm/second. The matrix resinstypically are fluorinated for reducing or minimizing interfacial mixingbetween the topcoat layer and underlying photoresist. One or morerepeating unit of the matrix resin can be fluorinated, for example, witha fluoroalkyl group such as a C1 to C4 fluoroalkyl group, typicallyfluoromethyl.

Exemplary matrix resin polymers in accordance with the invention includethe following:

wherein x is from 0 to 90 wt % (weight percent) and y is from 10 to 100wt %, based on the weight of the polymer. In an exemplary first matrixpolymer, x/y is 90/10 wt %;

wherein x is from 0 to 85 wt %, y is from 10 to 80 wt % and z is from 5to 20 wt % based on the weight of the polymer. In an exemplary matrixpolymer, x/y/z are 40/45/15 wt %; and

wherein x is from 0 to 85 wt %, y is from 10 to 80 wt % and z is from 5to 20 wt % based on the weight of the polymer. In an exemplary matrixpolymer, x/y/z are 40/45/15 wt %.

A first additive resin is provided in the topcoat composition to improvesurface properties at the topcoat/immersion fluid interface. Inparticular, the first additive resin can beneficially increase theimmersion fluid receding angle at the topcoat/immersion fluid interface,thereby allowing for faster scanning speeds. The first additive resinshould have a significantly lower surface energy than and besubstantially immiscible with the matrix polymer resin and otheradditive resins present in the system. In this way, the topcoat layercan be self-segregating, wherein the first additive resin migrates tothe surface of the topcoat layer apart from other resins during coating.The resulting topcoat layer is thereby graded, being rich in the firstadditive resin at the topcoat/immersion fluid interface. The firstadditive resin may further include one or more acid labile functionalgroups to enhance solubility in a developer solution after processingthe photoresist, for example, after exposure to activating radiation andpost-exposure baking. The first additive resin typically has excellentdevelopability both before and after photolithographic treatment. Thisresin typically exhibits a dark field developer dissolution rate, forexample, of 1 Å/second or higher.

Exemplary first additive resins in accordance with the invention includeas polymerized units monomers of the formulae M1, M2 and M3 as follows:

wherein R₁'s are independently hydrogen or a C1 to C6 optionallysubstituted alkyl or fluoroalkyl group, R₂ is an optionally substitutedcycloalkyl such as cyclohexyl, or branched alkyl group, for example, anisoalkyl group such as isopropyl or isobutyl, R₃ is an optionallysubstituted alkylene group, R₄ and R₅ are independently C1 to C4fluoroalkyl groups such as fluoromethyl or fluoroethyl, R6 is anoptionally substituted C1 to C6 alkylene, for example, ethylene orpropylene, R7 is a C1 to C4 fluoroalkyl group such as fluoromethyl orfluoroethyl and R8 is an acid labile leaving group, preferably having alow activation energy. Suitable monomers containing such acid labileleaving groups for use in the first additive resin include, for example,the following:

wherein R₁ is as defined above with respect to monomers M1-M3. Each ofmonomers M1, M2 and M3 in the foregoing exemplary formulas are believedto provide beneficial characteristics to the first additive resin. Forexample, it is believed that: monomer M1 allows for enhanced dynamiccontact angles, for example, increased receding angle and decreasedsliding angle, and for improving developer affinity and solubility;monomer M2 improves dark field developer dissolution rate whilemaintaining beneficial dynamic contact angles; and monomer M3 providesfor enhanced developer dissolution in exposed areas due to theacid-labile groups, and improves dynamic contact angles, particularlyincreasing the immersion fluid receding angle to, for example, greaterthan 72°.

A second additive resin is provided in addition to the matrix resin andfirst additive resin, typically for purposes of tuning the resistfeature profile and for controlling resist top loss. The second additiveresin typically includes one or more strong acid functional groups, forexample, a sulfonic acid group. Typically, the second additive resinincludes one or more sulfonic acid functional groups. The secondadditive resin should be miscible with the matrix polymer while, asdiscussed above, generally immiscible with the first additive resin.

Exemplary polymers useful in the invention as the second additive resininclude the following:

wherein x is from 0 to 89 wt %, y is from 10 to 99 wt % and z is from 1to 5 wt % based on the weight of the polymer. In an exemplary polymer,x/y/z are 10/85/5 wt %;

wherein x is from 5 to 20 wt %, y is from 75 to 94 wt % and z is from 1to 5 wt % based on the weight of the polymer. In an exemplary polymer,x/y/z are 15/80/5 wt %;

wherein x is from 5 to 20 wt %, y is from 75 to 94 wt % and z is from 1to 5 wt % based on the weight of the polymer;

wherein x is from 0 to 89 wt %, y is from 10 to 99 wt % and z is from 1to 5 wt % based on the weight of the polymer. In an exemplary polymer,x/y/z are 10/87/3 wt %;

wherein x is from 5 to 20 wt %, y is from 75 to 94 wt % and z is from 1to 5 wt % based on the weight of the polymer. In an exemplary polymer,x/y/z are 15/82/3 wt %; and

wherein x is from 5 to 20 wt %, y is from 75 to 94 wt % and z is from 1to 5 wt % based on the weight of the polymer. In an exemplary polymer,x/y/z are 10/87/3 wt %.

As discussed above, the topcoat compositions may contain one or moreacid generator compounds, for example, one or more thermal acidgenerator compounds and/or one or more photoacid generator compounds.Optionally, the topcoat compositions may be free of such acid generatorcompounds. In this regard, acid generator compounds can be provided bymigration from the underlying photoresist into the topcoat layer duringprocessing making their separate addition as part of the topcoatcompositions unnecessary. If desired, suitable photoacid generatorcompounds for use in the topcoat composition are discussed below withrespect to photoresist compositions and particularly include non-ioniccompounds such as imidosulfonates, for example, compounds of thefollowing formula:

wherein R is camphor, adamantane, alkyl (e.g. C₁₋₁₂ alkyl) andperfluoroalkyl such as perfluoro(C₁₋₁₂alkyl), particularlyperfluorooctanesulfonate and perfluorononanesulfonate. A particularlypreferred photoacid generator compound for use in a topcoat compositionis N-[(perfluorooctanesulfonyl)oxy]-5-norbornene-2,3-dicarboximide.

Thermal acid generator compounds also may be employed in topcoatcompositions of the invention including ionic or substantially neutralthermal acid generators, for example, an ammonium arenesulfonate salt.

If employed, one or more acid generators may be utilized in relativelysmall amounts in a topcoat composition, for example, 0.1 to 10 wt % ofthe total of the dry components of the composition (all componentsexcept solvent carrier), such as about 2 wt % of the total drycomponents.

Such use of one or more acid generator compounds can favorably impactlithographic performance, particularly resolution, of the developedimage patterned in an underlying resist layer.

A further optional additive of topcoat compositions of the invention areone or more surfactants, which can promote formation of a substantiallyuniform coating layer of the overcoated composition. A variety ofsurfactants may be employed. Typical surfactants exhibit an amphiphilicnature, meaning that they can be both hydrophilic and hydrophobic at thesame time. Amphiphilic surfactants possess a hydrophilic head group orgroups, which have a strong affinity for water and a long hydrophobictail, which is organophilic and repels water. Suitable surfactants maybe ionic (i.e., anionic, cationic) or nonionic. Further examples ofsurfactants include silicone surfactants, poly(alkylene oxide)surfactants, and fluorochemical surfactants. Suitable non-ionicsurfactants for use in the aqueous solution include, but are not limitedto, octyl and nonyl phenol ethoxylates such as TRITON® X-114, X-102,X-45, X-15 and alcohol ethoxylates such as BRIJ® 56(C₁₆H₃₃(OCH₂CH₂)₁₀OH)(ICl), BRIJ® 58 (C₁₆H₃₃(OCH₂CH₂)20OH)(ICl). Stillfurther exemplary surfactants include alcohol (primary and secondary)ethoxylates, amine ethoxylates, glucosides, glucamine, polyethyleneglycols, poly(ethylene glycol-co-propylene glycol), or other surfactantsdisclosed in McCutcheon's Emulsifiers and Detergents, North AmericanEdition for the Year 2000 published by Manufacturers ConfectionersPublishing Co. of Glen Rock, N.J.

Nonionic surfactants that are acetylenic diol derivatives also can besuitable, including such surfactants of the following formulae:

wherein in those formulae R₁ and R₄ are a straight or a branched alkylchain suitably having from 3 to 10 carbon atoms; R₂ and R₃ are either Hor an alkyl chain suitably having from 1 to 5 carbon atoms; and m, n, p,and q are numbers that range from 0 to 20. Such surfactants arecommercially available from Air Products and Chemicals, Inc. ofAllentown, Pa. trade names of SURFYNOL® and DYNOL®.

Additional suitable surfactants for use in coating compositions of theinvention include other polymeric compounds such as the tri-blockEO-PO-EO co-polymers PLURONIC® 25R2, L121, L123, L31, L81, L101 and P123(BASF, Inc.).

One or more surfactants may be suitably present in relatively smallamounts, for example, less than 5, 4, 3, 2, 1 or 0.5 weight percentrelative to weight of total solids (total solids being all compositionscomponents except solvent carrier).

Preferred topcoat composition layers will have an index of refraction ofabout 1.4 or greater at 193 nm including about 1.47 or greater at 193nm. Additionally, for any particular system, the index of refraction canbe tuned by changing the composition of one or more resins of thetopcoat composition, including by altering the ratio of components of aresin blend, or composition of any of the resin(s) of a topcoatcomposition. For instance, increasing the amount of organic content in atopcoat layer composition can provided increased refractive index of thelayer.

Preferred topcoat layer compositions will have a refractive indexbetween of the immersion fluid and the refractive index of thephotoresist at the target exposure wavelength, for example, 193 nm or248 nm.

Typical solvent materials to formulate and cast a topcoat compositionare any which dissolve or disperse the components of the topcoat layercomposition but do not appreciably dissolve an underlying photoresistlayer. More particularly, suitable solvents to formulate a topcoatcomposition include one or more of, but are not limited to, alcoholssuch as n-butanol, alkylene glycols, such as propylene glycol.Alternatively non-polar solvents such as aliphatic and aromatichydrocarbons, and alkyl ethers such as dodecane, isooctane and isopentylether may be used. One or more solvent in the solvent system canindividually be in a substantially pure form, meaning isomers of thesolvent molecule are present in that solvent in an amount less than 5 wt%, for example, less than 2 wt % or less than 1 wt %. Optionally, thesolvent can include a mixture of isomers of the solvent molecule,wherein the isomers are present in an amount greater than 5 wt %, forexample, greater than 10 wt %, greater than 20 wt %, greater than 40 wt%, greater than 60 wt %, greater than 80 wt % or greater than 90 wt %.Preferably, a mixture of different solvents, for example, two, three ormore solvents, is used to achieve effective phase separation of thesegregating, first additive resin from other polymer(s) in thecomposition and to reduce the viscosity of the formulation which allowsfor reduction in the dispense volume.

In an exemplary aspect, a three-solvent system can be used in thetopcoat compositions of the invention. The solvent system can include,for example, a primary solvent, a thinner solvent and an additivesolvent. The primary solvent typically exhibits excellent solubilitycharacteristics with respect to the non-solvent components of the topcoat composition. While the desired boiling point of the primary solventwill depend on the other components of the solvent system, the boilingpoint is typically less than that of the additive solvent, with aboiling point of from 120 to 140° C. such as about 130° C. beingtypical. Suitable primary solvents include, for example, C4 to C8n-alcohols, such as n-butanol, isobutanol, 2-methyl-1-butanol,isopentanol, 2,3-dimethyl-1-butanol, 4-methyl-2-pentanol, isohexanol andisoheptanol, isomers thereof and mixtures thereof. The primary solventis typically present in an amount of from 30 to 80 wt % based on thesolvent system.

The thinner solvent is present to lower the viscocity and improvecoating coverage at a lower dispensing volume. The thinner solvent istypically a poorer solvent for the non-solvent components of thecomposition relative to the primary solvent. While the desired boilingpoint of the thinner solvent will depend on the other components of thesolvent system, a boiling point of from 140 to 180° C. such as about170° C. is typical. Suitable thinner solvents include, for example,alkanes such as C8 to C12 n-alkanes, for example, n-octane, n-decane anddodecane, isomers thereof and mixtures of isomers thereof; and/or alkylethers such as those of the formula R₁—O—R₂, wherein R₁ and R₂ areindependently chosen from C₂ to C₈ alkyl, C₂ to C₆ alkyl and C₂ to C₄alkyl. The alkyl ether groups can be linear or branched, and symmetricor asymmetric. Particularly suitable alkyl ethers include, for example,isobutyl ether, isopentyl and isobutyl isohexyl, isomers thereof andmixtures thereof. The thinner solvent is typically present in an amountof from 10 to 70 wt % based on the solvent system.

The additive solvent is present to facilitate phase separation betweenthe phase segregation resin and other resin(s) in the topcoatcomposition to facilitate a graded topcoat structure. In addition, thehigher boiling point additive solvent can reduce the tip drying effectduring coating. It is typical for the additive solvent to have a higherboiling point than the other components of the solvent system. While thedesired boiling point of the additive solvent will depend on the othercomponents of the solvent system, a boiling point of from 170 to 200° C.such as about 190° C. is typical. Suitable additive solvents include,for example, hydroxy alkyl ethers, such as those of the formula:R₁—O—R₂—O—R₃—OHwherein R₁ is an optionally substituted C1 to C2 alkyl group and R₂ andR₃ are independently chosen from optionally substituted C2 to C4 alkylgroups, and mixtures of such hydroxy alkyl ethers including isomericmixtures. Exemplary hydroxy alkyl ethers include dialkyl glycolmono-alkyl ethers and isomers thereof, for example, diethylene glycolmonomethyl ether, dipropylene glycol monomethyl ether, isomers thereofand mixtures thereof. The additive solvent is typically present in anamount of from 3 to 15 wt % based on the solvent system.

A particularly suitable three-solvent system includes4-methyl-2-pentanol/isopentyl ether/dipropylene glycol monomethyl etherin a ratio by weight of 49/45/6. While the exemplary solvent system hasbeen described with respect to a three-component system, it should beclear that additional solvents may be used. For example, one or moreadditional primary solvent, thinner solvent, additive solvent and/orother solvent may be employed.

A topcoat or composition may be suitably prepared by admixture of theresins into one or more polar solvents such as those identified above oralternatively one or more non-polar solvents such as the aliphatic andaromatic hydrocarbons identified above. The viscocity of the entirecomposition is typically from 1.5 to 2 centipoise (cp), for example,from 1.6 to 1.9 cp, and is typically about 1.8 cp.

The examples which follows provide exemplary preparations of topcoatcompositions of the invention.

Photoresists

A wide variety of photoresist compositions may be used in combinationwith topcoat layer compositions and processes of the invention.

As discussed above, typical photoresists for use in accordance with theinvention include positive-acting or negative-acting chemicallyamplified photoresists, i.e., positive-acting resist compositions whichundergo a photoacid-promoted deprotection reaction of acid labile groupsof one or more composition components to render exposed regions of acoating layer of the resist more soluble in an aqueous developer thanunexposed regions, and negative-acting resist compositions which undergoa photoacid-promoted crosslinking reaction to render exposed regions ofa coating layer of the resist less developer soluble than unexposedregions. Of these, positive-acting materials are typical. Ester groupsthat contain a tertiary non-cyclic alkyl carbon (e.g., t-butyl) or atertiary alicyclic carbon (e.g., methyladamantyl) covalently linked tothe carboxyl oxygen of the ester are often preferred photoacid-labilegroups of resins employed in photoresists of lithography systems of theinvention. Acetal photoacid-labile groups also will be preferred.

The photoresists useful in accordance with the invention typicallycomprise a resin component and a photoactive component. Typically, theresin has functional groups that impart alkaline aqueous developabilityto the resist composition. For example, typical are resin binders thatcomprise polar functional groups such as hydroxyl or carboxylate.Typically, a resin component is used in a resist composition in anamount sufficient to render the resist developable with an aqueousalkaline solution.

For imaging at wavelengths greater than 200 nm, such as 248 nm, phenolicresins are typical. Typical phenolic resins are poly (vinylphenols)which may be formed by block polymerization, emulsion polymerization orsolution polymerization of the corresponding monomers in the presence ofa catalyst. Vinylphenols useful for the production of polyvinyl phenolresins may be prepared, for example, by hydrolysis of commerciallyavailable coumarin or substituted coumarin, followed by decarboxylationof the resulting hydroxy cinnamic acids. Useful vinylphenols may also beprepared by dehydration of the corresponding hydroxy alkyl phenols or bydecarboxylation of hydroxy cinnamic acids resulting from the reaction ofsubstituted or nonsubstituted hydroxybenzaldehydes with malonic acid.Preferred polyvinylphenol resins prepared from such vinylphenols have amolecular weight range of from about 2,000 to about 60,000 daltons.

Also typical for imaging at wavelengths greater than 200 nm, such as 248nm are chemically amplified photoresists that comprise in admixture aphotoactive component and a resin component that comprises a copolymercontaining both phenolic and non-phenolic units. For example, onetypical group of such copolymers has acid labile groups substantially,essentially or completely only on non-phenolic units of the copolymer,particularly alkylacrylate photoacid-labile groups, i.e., aphenolic-alkyl acrylate copolymer. One especially preferred copolymerbinder has repeating units x and y of the following formula:

wherein the hydroxyl group is present at either the ortho, meta or parapositions throughout the copolymer, and R′ is an optionally substitutedalkyl having 1 to about 18 carbon atoms, more typically 1 to about 6 to8 carbon atoms. Tert-butyl is a generally preferred R′ group. An R′group may be optionally substituted by, for example, one or more halogen(particularly F, Cl or Br), C₁₋₈ alkoxy, C₂₋₈ alkenyl, etc. The units xand y may be regularly alternating in the copolymer, or may be randomlyinterspersed through the polymer. Such copolymers can be readily formed.For example, for resins of the above formula, vinyl phenols and anoptionally substituted alkyl acrylate such as t-butylacrylate and thelike may be condensed under free radical conditions as known in the art.The substituted ester moiety, i.e., R′—O—C(═O)—, moiety of the acrylateunits serves as the acid labile groups of the resin and will undergophotoacid induced cleavage upon exposure of a coating layer of aphotoresist containing the resin. Typically, the copolymer will have aM_(w) of from about 8,000 to about 50,000, more typically about 15,000to about 30,000 with a molecular weight distribution of about 3 or less,more typically a molecular weight distribution of about 2 or less.Non-phenolic resins, for example, a copolymer of an alkyl acrylate suchas t-butylacrylate or t-butylmethacrylate and a vinyl alicyclic such asa vinyl norbornanyl or vinyl cyclohexanol compound, also may be used asa resin binder in compositions of the invention. Such copolymers alsomay be prepared by such free radical polymerization or other knownprocedures and suitably will have a M_(w) of from about 8,000 to about50,000, and a molecular weight distribution of about 3 or less.

Other typical resins that have acid-labile deblocking groups for use ina positive-acting chemically-amplified photoresist of the invention havebeen disclosed in European Published Application EP0829766A2 (resinswith acetal and ketal resins) and European Published ApplicationEP0783136A2 (terpolymers and other copolymers including units of 1)styrene; 2) hydroxystyrene; and 3) acid labile groups, particularlyalkyl acrylate acid labile groups such as t-butylacrylate ort-butylmethacrylate). In general, resins having a variety of acid labilegroups will be suitable, such as acid sensitive esters, carbonates,ethers, imides, etc. The photoacid labile groups will more typically bependant from a polymer backbone, although resins that have acid labilegroups that are integral to the polymer backbone also may be employed.

For imaging at sub-200 nm wavelengths such as 193 nm, a typicalphotoresist contains one or more polymers that are substantially,essentially or completely free of phenyl or other aromatic groups. Forexample, for sub-200 nm imaging, typical photoresist polymers containless than about 5 mole percent (mole %) aromatic groups, more typicallyless than about 1 or 2 mole % aromatic groups, more typically less thanabout 0.1, 0.02, 0.04 and 0.08 mole % aromatic groups, and still moretypically less than about 0.01 mole % aromatic groups. Particularlyuseful polymers are completely free of aromatic groups. Aromatic groupscan be highly absorbing of sub-200 nm radiation and thus are generallyundesirable for polymers used in photoresists imaged with such shortwavelength radiation.

Suitable polymers that are substantially or completely free of aromaticgroups and may be formulated with a PAG to provide a photoresist forsub-200 nm imaging are disclosed in European Published ApplicationEP930542A1 and U.S. Pat. Nos. 6,692,888 and 6,680,159.

Suitable polymers that are substantially or completely free of aromaticgroups suitably contain acrylate units such as photoacid-labile acrylateunits as may be provided by polymerization of methyladamanatylacrylate,methyladamantylmethacrylate, ethylfenchylacrylate,ethylfenchylmethacrylate, and the like; fused non-aromatic alicyclicgroups such as may be provided by polymerization of a norbornenecompound or other alicyclic compound having an endocyclic carbon-carbondouble bond; an anhydride such as may be provided by polymerization ofmaleic anhydride and/or itaconic anhydride; and the like.

Negative-acting photoresist compositions useful in the inventioncomprise a mixture of materials that will cure, crosslink or harden uponexposure to acid, and a photoactive component of the invention.Particularly useful negative acting compositions comprise a resin bindersuch as a phenolic resin, a crosslinker component and a photoactivecomponent. Such compositions and the use thereof have been disclosed inEuropean Patent Nos. 0164248B1 and 0232972B1, and in U.S. Pat. No.5,128,232. Typical phenolic resins for use as the resin binder componentinclude novolaks and poly(vinylphenol)s such as those discussed above.Typical crosslinkers include amine-based materials, including melamine,glycolurils, benzoguanamine-based materials and urea-based materials.Melamine-formaldehyde resins are generally most typical. Suchcrosslinkers are commercially available, for example: the melamineresins sold by Cytec Industries under the trade names Cymel 300, 301 and303; glycoluril resins sold by Cytec Industries under the trade namesCymel 1170, 1171, 1172; urea-based resins sold by Teknor Apex Companyunder the trade names Beetle 60, 65 and 80; and benzoguanamine resinssold by Cytec Industries under the trade names Cymel 1123 and 1125.

For imaging at sub-200 nm wavelengths such as 193 nm, typicalnegative-acting photoresists are disclosed in International ApplicationPub. No. WO 03077029.

The resin component of resists useful in the invention are typicallyused in an amount sufficient to render an exposed coating layer of theresist developable such as with an aqueous alkaline solution. Moreparticularly, a resin binder will suitably comprise 50 to about 90 wt %of total solids of the resist. The photoactive component should bepresent in an amount sufficient to enable generation of a latent imagein a coating layer of the resist. More specifically, the photoactivecomponent will suitably be present in an amount of from about 1 to 40 wt% of total solids of a resist. Typically, lesser amounts of thephotoactive component will be suitable for chemically amplified resists.

The resist compositions useful in the invention also comprise a PAGemployed in an amount sufficient to generate a latent image in a coatinglayer of the resist upon exposure to activating radiation. Typical PAGsfor imaging at 193 nm and 248 nm imaging include imidosulfonates such ascompounds of the following formula:

wherein R is camphor, adamantane, alkyl (e.g., C₁₋₁₂ alkyl) orperfluoroalkyl such as perfluoro(C₁₋₁₂alkyl), particularlyperfluorooctanesulfonate and perfluorononanesulfonate. A specificallypreferred PAG isN-[(perfluorooctanesulfonyl)oxy]-5-norbornene-2,3-dicarboximide.

Sulfonate compounds are also suitable PAGs, particularly sulfonatesalts. Two suitable agents for 193 nm and 248 nm imaging are thefollowing PAGs 1 and 2:

Such sulfonate compounds can be prepared as disclosed in European PatentNo. 0783136B1, which details the synthesis of above PAG 1.

Also suitable are the above two iodonium compounds complexed with anionsother than the above-depicted camphorsulfonate groups. In particular,typical anions include those of the formula RSO₃— where R is adamantane,alkyl (e.g. C₁₋₁₂ alkyl) and perfluoroalkyl such as perfluoro(C₁₋₁₂alkyl), particularly perfluorooctanesulfonate,perfluorobutanesulfonate and the like.

Other known PAGs also may be employed in photoresists used in accordancewith the invention. Particularly for 193 nm imaging, generally typicalare PAGs that do not contain aromatic groups, such as theabove-mentioned imidosulfonates, in order to provide enhancedtransparency.

A typical optional additive of the resists is an added base,particularly tetrabutylammonium hydroxide (TBAH), or tetrabutylammoniumlactate, which can enhance resolution of a developed resist reliefimage. For resists imaged at 193 nm, a typical added base is a hinderedamine such as diazabicyclo undecene or diazabicyclononene. The addedbase is suitably used in relatively small amounts, for example, about0.03 to 5 wt % relative to the total solids.

Photoresists used in accordance with the invention also may containother optional materials. For example, other optional additives includeanti-striation agents, plasticizers and speed enhancers. Such optionaladditives typically will be present in minor concentrations in aphotoresist composition except for fillers and dyes which may be presentin relatively large concentrations, for example, in amounts of fromabout 5 to 30 wt % based on the total weight of a resist's drycomponents.

Negative-acting photoresists useful in the invention typically willcontain a crosslinking component. The crosslinking component istypically present as a separate resist component. Amine-basedcrosslinkers often will be preferred such as a melamine, for example,the Cymel melamine resins.

The photoresists useful in the invention are generally preparedfollowing known procedures. For example, a resist of the invention canbe prepared as a coating composition by dissolving the components of thephotoresist in a suitable solvent, for example, a glycol ether such as2-methoxyethyl ether (diglyme), ethylene glycol monomethyl ether,propylene glycol monomethyl ether; propylene glycol monomethyl etheracetate; lactates such as ethyl lactate or methyl lactate, with ethyllactate being preferred; propionates, particularly methyl propionate,ethyl propionate and ethyl ethoxy propionate; a Cellosolve ester such asmethyl Cellosolve acetate; an aromatic hydrocarbon such toluene orxylene; or a ketone such as methylethyl ketone, cyclohexanone and2-heptanone. Typically the solids content of the photoresist variesbetween 5 and 35 wt % based on the total weight of the photoresistcomposition. Blends of such solvents also are suitable.

Lithographic Processing

Liquid photoresist compositions can be applied to a substrate such as byspin coating, dipping, roller coating or other conventional coatingtechnique, with spin coating being typical. When spin coating, thesolids content of the coating solution can be adjusted to provide adesired film thickness based upon the specific spinning equipmentutilized, the viscosity of the solution, the speed of the spinner andthe amount of time allowed for spinning.

Photoresist compositions used in accordance with the invention aresuitably applied to substrates conventionally used in processesinvolving coating with photoresists. For example, the composition may beapplied over silicon wafers or silicon wafers coated with silicondioxide for the production of microprocessors and other integratedcircuit components. Aluminum-aluminum oxide, gallium arsenide, ceramic,quartz, copper, glass substrates and the like may also be suitablyemployed. Photoresists also may be suitably applied over anantireflective layer, particularly an organic antireflective layer.

A topcoat composition of the invention can be applied over thephotoresist composition by any suitable method such as described abovewith reference to the photoresist compositions, with spin coating beingtypical.

Following coating of the photoresist onto a surface, it may be dried byheating to remove the solvent until typically the photoresist coating istack free, or as discussed above, the photoresist layer may be driedafter the topcoat layer composition has been applied and the solventfrom both the photoresist composition and topcoat composition layerssubstantially removed in a single thermal treatment step.

The photoresist layer with topcoat composition layer is then exposed topatterned radiation activating for the photoactive component of thephotoresist.

In an immersion lithography system, the space between the exposure tool(particularly the projection lens) and the photoresist coated substrateis occupied by an immersion fluid, such as water or water mixed with oneor more additives such as cesium sulfate which can provide a fluid ofenhanced refractive index. Typically, the immersion fluid (e.g., water)has been treated to avoid bubbles, for example, degassing the water toavoid nanobubbles.

References herein to “immersion exposing” or other similar termindicates that exposure is conducted with such a fluid layer (e.g. wateror water with additives) interposed between an exposure tool and thecoated photoresist composition layer.

During the exposure step (whether immersion where fluid is interposed,or non-immersion where such fluid is not interposed), the photoresistcomposition layer is exposed to patterned activating radiation with theexposure energy typically ranging from about 1 to 100 mJ/cm², dependentupon the exposure tool and the components of the photoresistcomposition. References herein to exposing a photoresist composition toradiation that is activating for the photoresist indicates that theradiation is capable of forming a latent image in the photoresist suchas by causing a reaction of the photoactive component, for example,producing photoacid from a photoacid generator compound.

As discussed above, photoresist compositions may be photoactivated by ashort exposure wavelength, particularly a sub-300 and sub-200 nmexposure wavelength, with 248 nm and 193 nm being particularly preferredexposure wavelengths, as well as EUV and 157 nm. Following exposure, thefilm layer of the composition is typically baked at a temperatureranging from about 70° C. to about 160° C.

Thereafter, the film is developed, typically by treatment with anaqueous base developer chosen from quaternary ammonium hydroxidesolutions such as a tetra-alkyl ammonium hydroxide solutions; aminesolutions, typically a 0.26 N tetramethylammonium hydroxide such asethyl amine, n-propyl amine, diethyl amine, di-n-propyl amine, triethylamine, or methyldiethyl amine; alcohol amines such as diethanol amine ortriethanol amine; and cyclic amines such as pyrrole or pyridine. Ingeneral, development is in accordance with procedures recognized in theart.

Following development of the photoresist coating over the substrate, thedeveloped substrate may be selectively processed on those areas bared ofresist, for example by chemically etching or plating substrate areasbared of resist in accordance with procedures known in the art. For themanufacture of microelectronic substrates, for example, the manufactureof silicon dioxide wafers, suitable etchants include a gas etchant suchas a halogen plasma etchant such as a chlorine- or fluorine-basedetchant such a Cl₂ or CF₄/CHF₃ etchant applied as a plasma stream. Aftersuch processing, resist may be removed from the processed substrateusing known stripping procedures.

The following non-limiting examples are illustrative of the invention.

EXAMPLES 1-5

Topcoat Composition Preparation

Topcoat compositions of the invention were prepared by admixing thefollowing components in the following amounts.

Example 1 Composition

-   1. 0.41 g of 13.3 wt % solution of    poly(4,4,4-trifluoro-3-hydroxy-1-methyl-3-(trifluoromethyl)butyl    2-methacrylate-co-2{[(trifluoromethyl)sulfonyl]amino}ethyl    2-methacrylate) (90/10 ratio by weight) in 4-methyl-2-pentanol-   2. 0.36 g of 10.0 wt % solution of    poly(2{[(trifluoromethyl)sulfonyl]amino}ethyl    2-methacrylate-co-2-Acrylamido-2-Methyl-1-propanesulfonic acid)    (95/5 ratio by weight) in 4-methyl-2-pentanol-   3. 0.05 g of 21.0 wt % solution of    poly(1,1,1-trifluor-2-hydroxy-6-methyl-2-(trifluoromethyl)heptane-4-yl    methacrylate-co-2-{[(trifluoromethyl)sulfonyl]amino}ethyl    2-methacrylate)-co-2,3,3-trimethyl 2-methacrylate) (55/25/20 ratio    by weight) in propylene glycol methyl ether acetate-   4. 0.15 g of dipropylene glycol monomethyl ether, mixture of isomers-   5. 0.5 g of isopentyl ether, mixture of isomers-   6. 3.53 g of 4-methyl-2-pentanol

Example 2 Composition

-   1. 0.41 g of 13.3 wt % solution of    poly(4,4,4-trifluoro-3-hydroxy-1-methyl-3-(trifluoromethyl)butyl    2-methacrylate-co-2{[(trifluoromethyl)sulfonyl]amino}ethyl    2-methacrylate) (90/10 ratio by weight) in 4-methyl-2-pentanol-   2. 0.36 g of 10.0 wt % solution of    poly(2{[(trifluoromethyl)sulfonyl]amino}ethyl    2-methacrylate-co-2-Acrylamido-2-Methyl-1-propanesulfonic acid)    (95/5 ratio by weight) in 4-methyl-2-pentanol-   3. 0.05 g of 21.0 wt % solution of    poly(1,1,1-trifluor-2-hydroxy-6-methyl-2-(trifluoromethyl)heptane-4-yl    methacrylate-co-2-{[(trifluoromethyl)sulfonyl]amino}ethyl    2-methacrylate)-co-2,3,3-trimethyl 2-methacrylate) (55/25/20 ratio    by weight) in propylene glycol methyl ether acetate-   4. 0.15 g of dipropylene glycol monomethyl ether, mixture of isomers-   5. 1.0 g of isopentyl ether, mixture of isomers-   6. 3.03 g of 4-methyl-2-pentanol

Example 3 Composition

-   1. 0.41 g of 13.3 wt % solution of    poly(4,4,4-trifluoro-3-hydroxy-1-methyl-3-(trifluoromethyl)butyl    2-methacrylate-co-2{[(trifluoromethyl)sulfonyl]amino}ethyl    2-methacrylate) (90/10 ratio by weight) in 4-methyl-2-pentanol-   2. 0.36 g of 10.0 wt % solution of    poly(2{[(trifluoromethyl)sulfonyl]amino}ethyl    2-methacrylate-co-2-Acrylamido-2-Methyl-1-propanesulfonic acid)    (95/5 ratio by weight) in 4-methyl-2-pentanol-   3. 0.05 g of 21.0 wt % solution of    poly(1,1,1-trifluor-2-hydroxy-6-methyl-2-(trifluoromethyl)heptane-4-yl    methacrylate-co-2-{[(trifluoromethyl)sulfonyl]amino}ethyl    2-methacrylate)-co-2,3,3-trimethyl 2-methacrylate) (55/25/20 ratio    by weight) in propylene glycol methyl ether acetate-   4. 0.15 g of dipropylene glycol monomethyl ether, mixture of isomers-   5. 1.5 g of isopentyl ether, mixture of isomers-   6. 2.53 g of 4-methyl-2-pentanol

Example 4 Composition

-   1. 0.41 g of 13.3 wt % solution of    poly(4,4,4-trifluoro-3-hydroxy-1-methyl-3-(trifluoromethyl)butyl    2-methacrylate-co-2{[(trifluoromethyl)sulfonyl]amino}ethyl    2-methacrylate) (90/10 ratio by weight) in 4-methyl-2-pentanol-   2. 0.36 g of 10.0 wt % solution of    poly(2{[(trifluoromethyl)sulfonyl]amino}ethyl    2-methacrylate-co-2-Acrylamido-2-Methyl-1-propanesulfonic acid)    (95/5 ratio by weight) in 4-methyl-2-pentanol-   3. 0.05 g of 21.0 wt % solution of    poly(1,1,1-trifluor-2-hydroxy-6-methyl-2-(trifluoromethyl)heptane-4-yl    methacrylate-co-2-{[(trifluoromethyl)sulfonyl]amino}ethyl    2-methacrylate)-co-2,3,3-trimethyl 2-methacrylate) (55/25/20 ratio    by weight) in propylene glycol methyl ether acetate-   4. 0.15 g of dipropylene glycol monomethyl ether, mixture of isomers-   5. 2.0 g of isopentyl ether, mixture of isomers-   6. 2.03 g of 4-methyl-2-pentanol

Example 5 Coating and Water Contact Angle Evaluations

The compositions of Examples 1-4 were spin coated on a dried photoresistlayer disposed on a silicon wafer substrate. Water contact angles wereevaluated for the coating compositions. The water contact anglesevaluated include static (θ_(Static)), receding (θ_(Receding)),advancing (θ_(Advancing)) and sliding (θ_(Sliding)) in generalaccordance with the procedures disclosed in Burnett et al., J. Vac. Sci.Techn. B, 23(6), pages 2721-2727 (November/December 2005). The resultsare set forth in Table 1, below.

TABLE 1 Contact Angles θ (°) Example θ_(Static) θ_(Receding)θ_(Advancing) θ_(Sliding) Example 1 90 73.4 92.7 24.5 Example 2 89.773.5 93.6 22.1 Example 3 89.4 73 92.7 26.1 Example 4 87.8 73.4 92.9 23.5

Example 6

Immersion Lithography

The coating compositions of Examples 1-4 are each spin coated onto arespective silicon wafer having a coating layer of adeblocking-methacrylate based 193 nm positive photoresist. Thephotoresist layer for each wafer is then imaged in an immersionlithography system with patterned radiation having a wavelength of 193nm.

What is claimed is:
 1. A composition suitable for use in forming atopcoat layer over a layer of photoresist, the composition comprising: afirst resin, a second resin and a third resin which are different fromeach other, wherein the first resin comprises one or more fluorinatedgroups and is present in the composition in a larger proportion byweight than the second and third resins individually, wherein the secondresin has a lower surface energy than a surface energy of the firstresin and the third resin, and wherein the third resin comprises one ormore strong acid groups.
 2. The composition of claim 1, wherein thefirst resin further comprises a sulfonamide.
 3. The composition of claim1, wherein the second resin comprises one or more photoacid-labilegroups.
 4. The composition of claim 1, wherein the one or more strongacid groups of the third resin comprise a sulfonic acid group.
 5. Thecomposition of claim 1, further comprising a solvent system comprising amixture of: an alcohol; an alkyl ether and/or an alkane; and a dialkylglycol mono-alkyl ether.
 6. A coated substrate, comprising: aphotoresist layer on a substrate; and a topcoat layer on the photoresistlayer, wherein the topcoat layer comprises: a first resin, a secondresin and a third resin which are different from each other, wherein thefirst resin comprises one or more fluorinated groups and is present inthe composition in a larger proportion by weight than the second andthird resins individually, wherein the second resin has a lower surfaceenergy than a surface energy of the first resin and the third resin, andwherein the third resin comprises one or more strong acid groups.
 7. Thecoated substrate of claim 6, wherein the topcoat layer is a gradedlayer.
 8. A method of processing a photoresist composition, comprising:(a) applying a photoresist composition over a substrate to form aphotoresist layer; (b) applying over the photoresist layer a topcoatcomposition, the composition comprising: a first resin, a second resinand a third resin which are different from each other, wherein the firstresin comprises one or more fluorinated groups and is present in thecomposition in a larger proportion by weight than the second and thirdresins individually, wherein the second resin has a lower surface energythan a surface energy of the first resin and the third resin, andwherein the third resin comprises one or more strong acid groups; and(c) exposing the photoresist layer to actinic radiation.
 9. The methodof claim 8, wherein the exposure is an immersion exposure and thesubstrate is a semiconductor wafer.
 10. The method of claim 8, whereinthe topcoat layer is a graded layer.